[Hallicrafters] SX-101 issue

[Jim Wilhite]

If you think that 560 may be the problem, replace it and hope that is where 
the problem is.  Have you cleaned all switches involved in the circuit, even 
a bit of corrosion on the switch contact can cause that problem as can dirty 
contacts on a variable cap, or loose contacts can change things as they 
heat.

The negative 4700 means 4700 parts per million per degree of temp change. 
The negative means it will change in the negative direction.

If the temp comp 10 pf is bad you may have a real challenge finding caps 
that will work.  Surplus Sales of Nebraska has a good selection so you can 
look there.  Another source is eBay just search for temperature compensating 
capacitors and sort through.    They may be expensive on eBay but if you 
really need it.

Another thing about replacing that cap.  If you do, be sure to heat sink the 
leads as you solder it.  They are a bit fragile when exposed to high heat 
and you don't want to ruin a new one when installing it.  Are you sure the 
bandswitch is good?  As I stated above a dirty contact in the oscillator 
section can cause that problem.

Jim
W5JO

-----Original Message----- 

Hi all,
I have been working on my SX-101 Mk 3A and have finished recapping the
whole radio. I have a small issue that was occurring before I decided to
recap the thing. When listening to a signal, (I pretty much just listen
to cw), it will all of a sudden change pitch as if changing frequency.
Im thinking it is in the BFO circuit. There are a couple of mica
capacitors in that circuit that Im thinking might be the culprits.One of
them is  560 PF 500v, and the other is a 10 pfd (N4700) ceramic. What
does the N4700 mean? What would I use to replace that particular cap?
Both of these caps are the flat rectangular style. There is also a
resistor in parallel with that cap that has a wire wound around it on
both ends. What would I use to replace that as well? Im not finding
resistors like that anywhere. If anyone has any other ideas as to what
the frequency jumping problem may be, Im open for suggestions.

Thanks-Bob-W0YBS